Addition to the resonance correction:
As far as I understand it: it's more analog than digital: dedicated motor current filter, proportional phase shift and speed detection.
So I looked at my spare G251 and it has a 14 pin LM324 and 14 pin LM339, this adds up to 8 analog "elements", the CPLD tutorial only has 2.....
The basic schematic on one of the patents (4675590) has 4 for the correction alone.